case 5 - teach me physiology bilirubin metabolism Flashcards
what are the two forms of bilirubin
conjugated and unconjugated
what is a classic feature of unconjugated bilirubin
it is insoluble in water
what does this mean for unconjugated bilirubin
it can only travel in the bloodstream if bound to albumin and it cannot be directly excreted from the body
where can conjugated bilirubin travel
it can travel through the blood without requiring transport proteins like albumin which means it can also be excreted out of the body
what cells are responsible for the maintenance of blood
reticuloendothelial cells. these are macrophages and maintain the blood through the destruction of old or abnormal cells
what is haem broken down into
iron and biliverdin,
what is this haem process catalysed by
haem oxygenase
what happens to the iron and the biliverdin
the iron gets recycled and the biliverdin is reduced to create unconjugated bilirubin
what facilitates unconjugated bilirubin’s transport to the liver
the binding of albumin
what happens once in the liver
the glucaronic acid is added to the unconjugated bilirubin
how is glucaronic acid added to this unconjugated bilirubin
by the enzyme glucoronyl transferase
what does this form
this forms conjugated bilirubin, which is soluble
what does this conjugated bilirubin allow for
the bilirubin to be excreted into the duodenum in bile
what happens once in the colon
colonic bacteria deconjugate bilirubin and convert it into urobilinogen
what happens to around 80% of this urobilinogen
is further oxidised by intestinal bacteria and converted to stercobilin and then excreted through faeces
